Seafloor In‐Situ Heat Flow Measurements in the Deep‐Water Areas of the Northern Slope, South China Sea

Abstract

AbstractSeafloor heat flow is the fundamental data for studying marine geodynamics and evaluating petroleum resource. However, there are only few heat flow measurement stations in the deepwater areas of the northern slope of the South China Sea, where abundant oil‐gas resources and gas hydrate have been found. To investigate the geothermal distribution in these deepwater areas where are thought to be advantaged for gas hydrates preservation, 16 seafloor in‐situ heat flow values were successfully obtained with Jianyu 1‐type probe in Xisha and Shenhu water areas. The results show that the heat flow values of both Xisha Trough and Baiyun sag are high. There are 3 stations located in the Xisha Trough. Except for one unreliable station, the heat flow values of the other two stations are 89±1 mW·m−2 and 87±1 mW·m−2 respectively, with corresponding geothermal gradient 105.3°C·km−1 and 99.3°C·km−1 respectively. The other 13 stations, with geothermal gradient varying from 58.5 to 100.7°C·km−1, are located in the center of the Baiyun Sag. Except for four stations with heat flow values below 70 mW·m−2,the heat flow values of the other stations vary from 75±2 to 101±4 mW·m−2 ,which are generally higher than those of the eastern Baiyun sag. Analyses suggest that the high thermal regime in Xisha Trough and Baiyun Sag might be related with high thermal background, latest faulting, diapiric and magma intrusion and hydrothermal activities.